Fair Value Measurements (Fair Value of Financial Liabilities Measured on Recurring Basis) (Details) - USD ($)	6 Months Ended	12 Months Ended
Jun. 30, 2019	Dec. 31, 2018
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Transfer of Liabilities From Level 1 to Level 2	$ 0	$ 0
Transfer of Liabilities From Level 2 to Level 1	0	0
Transfer of Liabilities Into Level 3	0	0
Transfer of Liabilities Out of Level 3	0	0
Total assets	3,166,000	9,430,000
Asset acquisition derivative liability		1,117,000
Total liabilities		1,117,000
Fair Value, Inputs, Level 1 [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Total assets	3,166,000	9,430,000
Fair Value, Inputs, Level 3 [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Asset acquisition derivative liability		1,117,000
Total liabilities		1,117,000
Money Market Funds [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Money market funds	3,166,000	9,430,000
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Schedule Of Derivative Liabilities At Fair Value [Line Items]
Money market funds	$ 3,166,000	$ 9,430,000

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Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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-Publisher FASB
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Fair value portion of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates.

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No definition available.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Amount of transfers of liabilities measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

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Amount of transfers of liabilities measured on a recurring basis out of Level 2 of the fair value hierarchy into Level 1.

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Amount of transfers of financial instrument classified as a liability into level 3 of the fair value hierarchy.

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Amount of transfers of financial instrument classified as a liability out of level 3 of the fair value hierarchy.

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Fair value of financial and nonfinancial obligations.

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